Foam inhibited lubricating oil composition



products of combustionyand the like.

United States atent if fitice 3,033,788 Patented May 8, 1962 I 3,033,788FOAM INHIBITED LUBRICATlNG OIL COMPOSITION Charles E; Trautman,Ches'wick, Pa.,=assignor to Gulf Research-=8: Development Company,Pittsburgh, Pa., a

corporation of Delaware NoDrawing. Filed'Mar. 19,1958,jSel'.' No.722,391 21 Claims. (Cl. 252-496) volume of foam or froth produced ismany times that of the original oil, and even with mild agitation,substantialamounts of foam are produced in many oil compositions. Inpreparing and using such oils and oil. compositions commercially, theyare subjected to agitation under a wide range cof conditions i andfrequently undesirable amounts "of; foam or.- froth are produced.

Various meansof combating such foaming of oilsand oil compositions havebeen proposed. For instance, mechanical devices have been proposed for.destroying or-xbreaking-foam as it is formed. Usually such devices havebeen cumbersome or inefficient, or both, and they are not generally usedcommercially. Likewise, the incorporation of certain oil-solublecompounds in .the oil has been proposed as a means for preventingfoaming, such ,compounds being called anti-foam agents. Unfortunately,no agent of this type has been found which is completely satisfactory inall types of oils under all conditions'of use. While some agents haveeffectively reduced foaming of oils maintained at room temperature,i.e., about 70 to about 80 F., the agents have been less effective inoils maintained at an elevated temperature. Some agents have effectivelyreduced foaming in light oils but they have been less effective inheavier oils, i.e., oils havinga viscosity above about 100- SUS at v100F. Some of the prior so called .anti-foam agents have been found even toincrease the amount of foam formed in mineral oils maintained at about200 F., particularly in theheavier-oils, i.e., oil s having a viscosityabove about 100 SUS at 100 F.

It is important to provide an oil which is markedly resistant to foamingatian elevated temperature as well as at room temperature. For example,in the lubrication of internal combustion engines such as automotive,aviation, diesel and like engines, the temperature of the oil in thecrankcase during engine operation is usually within the range'ofabout'l00" to about 225 F. In lubricating such engines, appreciablefoaming of the oil seria ously interferes with effective lubrication. Bythe present inventionsuch foaming is eifectively reduced. My

new anti-foam agents and=compositions are also useful in otherhydrocarbon oils and oil compositions in which they are substantiallyinsoluble whether used as a lubricaritforvnotand whether the temperatureof the oil is at room-temperature or at an elevated temperature. Theanti-foam agents and compositions of the present invention, however, areparticularly eifective in combating foaming'in :mineral oils, especiallythe heavier mineral oils and lubricants at temperatures between about100 and 225 'F.

It xis therefore among thewobjects achieved by this invention to-providean improved method of; preventing foaming of hydocarbon oils,particularly mineral oils and oil compositions containing them, in whichthe normal foaming tendency .of the oil is effectively: abated orsuppressed for long periods of use without deleteriously affectingtheotherproperties of the :oil.

Another object achieved by he presentinvention isthe provision of new'andimproved anti-foam agents and compositions capable .of abatingandinhibiting foaming of hydrocarbonoils and oil. compositions whendispersed 1 therein in minute amounts.

A further object achieved by the present invention is the provision ofnewand improvedoil compositions, particularly improved mineral oils andlubricants having marked resistance tofoaming and other advantageousproperties including resistance to emulsification and containing minuteamounts of .an oil-insoluble anti-foam agent finely dispersed therein.

1 have discovered that the foaming of hydrocarbon oils, particularlymineral oils and compositions containing them, can be eifectivelysuppressed .or prevented without substantial modification of thedesirable properties of'such oils by forming in the oil a stable, finedispersion of a small amount of an organo-silicate which has'beensubjected to ionizing radiation for a time suflicient for saidorgano-silicate to absorb at least about 6 megareps. of radiation. Ihave found that an oil con- -taining such an irradiated organo-silicateas va stable,

finely dispersed phase is markedly resistant to: foaming even under themost violent conditions encountered in commercial practice. The presenceof'the finely dis persed irradiated organo-silicate in the oilapparently causes the film of the oil foam to ruptu-rethereby quicklydestroying the foam. .In fact, particularly when an adequate amount ofirradiated organo-silicate is used, its presence so rapidly breaks theoil foam that substantially all foam is destroyed as fast as it isformed.

.1 have found-that an anti-foam agent comprising an organo-silicatecan'be converted to an improvedproduct bysubjecting the organo-silicateto ionizing radiation for 'a time sufficient for said organo-silicate toabsorb at least about 6 megareps. of radiation while removing heattherefrom at a rate sufiicientto maintain the bulb temperature of theorgano-silicate below its decomposition or vaporization point. Forexample, I have found that in order to obtain a product which willmaterially reduce the foaming of an oil having a viscosity above. about100 SUS atl100 F.1at temperatures up to about 225 F., the total amountof energy absorbed by the organosilicate should be at least about 6,preferably between about 6 and about 1000 megareps. If less than 6megareps. of energy is absorbed, the irradiated product is .notsubstantially improved with respect to its anti-foam properties forheavy oils over the unirradiated organosilicate. While more than about1000 megareps, of energy can be absorbed by the organo-silicate, theincrement of improvement per megarep. of energy absorbed may beprogressively smaller, thus rendering further irradiation economicallyunattractive. A megarep. (mrep.) is equal to one million reps. A 'rep.is defined as that dose of any ionizing radiation which produces energyabsorption of 83.8 ergs pergram of material.

While the total amount of energy which must be absorbed by theorgano-silicate to obtain-the desired product is critical, extreme caremust be exercised in irradiating the organo-silicate. During irradiationthe organosilicate absorbs the high energy particles which are moving ata high rate of speed. This movement is transferred upon absorption inpart into heat. If irradiation is left no controlled and is perrnittedto proceed at too great a tion and degradation thereof takesplace.Desirably the organo-silicate being irradiated should be maintainedduring the irradiation period at a temperature as near theorgano-silicate input temperature as possible so that the changes takingplace in the organo-silicate are those resulting from irradiation ratherthan from heat.

Heat resulting from irradiation can be removed from the organo-silicatein many ways. One method comprises subjecting the organo-silicate toionizing radiation, removing the organo-silicate from the radiation zoneas the temperature thereof rises, reducing the temperature of theorgano-silicate to a low temperature, such as about 70 to about 150 F.,by recycling to a cooling zone, recycling said cooled organo-silicate tothe radiation zone, and thereafter continuing such cycle until theorganosilicate has absorbed the required amount of energy. Anothermethod, though not preferred, because of the poor heat conductivity ofan organo-silicate, resides in the use of cooling coils immersed in theorgano-silicate being irradiated to remove the heat therefrom.

The time required for irradiation is extremely important from aneconomic point of view. When the process is carried out over an extendedperiod of time, it becomes unattractive for commercial use. At the sametime, irradiating the organo-silicate in too short a time makes itextremely difiicult to control the reaction and to maintain theorgano-silicate within the desired temperature limits. I have found, forexample, that an irradiation period per gram of material beingirradiated of about 0.1 to about 20 seconds is sufficient to eiiect thedesired result if a 2 million volt Van de Graalf accelerator producingan electron beam at an output of 500 watts is used. With other powersources, or" course, the time will be changed in accordance with thepower of the source. Provided heat is removed at a rate sufiicient toprevent substantial decomposition or vaporization of theorgano-silicate, any irradiation rate can be employed, though extremelyhigh rates may involve technical difliculties.

I do not wish to limit this invention to any particular method ofradiation inasmuch as the etfects of radiation on organo-silicates areessentially the same insofar as anti-foam characteristics are concernedregardless of the radiation source. Ionizing radiations can be obtained,for example, using radio isotopes, nuclear reactors or high energyparticle accelerators. Examples of radio isotopes which can be used arecobalt 60 for gamma and strontium 90 for beta. Operating nuclearreactors of intermediate or full power size can be used as a source foreither gamma rays or neutrons or both. Particle accelerators such as thecyclotron, bevatron, synchrotron, Van de Graafif, or X-ray machines canalso be used.

In effecting irradiation of the organo-silicate, the organo-silicate canbe introduced into a well in a nuclear reactor or through a tube whichtraverses the reactor. In some instances where it is desirable to exposethe organo-silicate to fast or high energy neutrons only, and in thesubstantial absence of beta and gamma radiation, the irradiation can beconducted outside of the reactor using a collimated beam of fastneutrons. Such a collimated beam of fast neutrons can be obtained, forexample, as described in U.S. Patent No. 2,708,656 to Enrico Fermi andLeo Szilard, by inserting a hollow shaft or tube into the centralportion of the reactor. Gamma rays can be screened from the fast neutronbeam by means of a sheet of bismuth metal extending across the path ofthe beam.

A neturon-free radiation source can be obtained directly from ahomogeneous reactor by separating the radioactive fission gases, xenonand krypton, from the reactor core by conventional or modifiedgas-liquid separating means. A continuous supply of the radioactivefission gases could be obtained from such a reactor. The fission gaseshave a very high intensity of beta and gamma radiation but a very shorthalf life. These gases possess about one percent of the total fissionenergy. The gases are chemically inert and therefore would not formundesired side reaction products.

While I am not certain as to the exact nature of the changes which takeplace when an organo-silicate is subjected to ionizing radiation, it ispossible that some cross linking occurs. However, I have noted nosignificant change in viscosity of a tetra alkyl ortho silicate whenirradiated to dosages of 6 to 50 megareps. of radiation. The viscosityand acid values of unirradiated and irradiated tetra(diisobutylcarbinyl)silicate for example, are as follows:

VISCOSITY F 210 F. Neut. Value Dosage Mreps. ASTM (D-974) CS SUS CS SUSIt will be noted that the viscosity and acid values of tetra(diisobutylcarbinyl)silicate were not significantly changed by irradiation.

In the practice of this invention, various irradiated oilinsolubleliquid organo-silicates having a surface tension lower than that of theoil and capable of being stably and finely dispersed in the oil may beemployed as antifoam agents.

The organo-silicates which are irradiated for use according to thisinvention are composed of one or more silicon atoms, each silicon atomhaving attached to it at least one (OR) radical.

When more than one silicon atom is present, the silicon atoms are linkedtogether through an oxygen atom. Typical organo-silicates which aresuitable for the purpose of the invention are the irradiated liquidalkyl ortho silicates, aryl ortho silicates, aralkyl ortho silicates,aralkyl ortho silicates, alkaryl ortho silicates and heterocyclic orthosilicates, including their irradiated condensation or polymerizationproducts.

The organo-silicates when polymerized may be straight chain products orthey may be products of cross polymerization or a mixture of straightchain and cross linked polymers. Thus, the organo-silicates useful forthe purpose of my invention may be represented by the formulae (I) R ()RR0- Si0 -SiOR o R OR and (II) (I) R 0 R (I) R RO sr-o si-o-st-oR OR OR(I) R (I) R RO- Si-O -SiO-SIOR OR a OR OR in which the several Rsrepresent the same or different alkyl, aryl, aralkyl, alkaryl orheterocyclic group and n is a number from 0 to 100 or higher dependingupon the number of organo-silicate residues in the complex molecule. Itwill be understood that the formula showing cross polymerization ismerely illustrative of cross polymerization products suitable for thepurpose of my in vention and such products may take other forms in whichtwo or more cross linkings between polymers are estabis zero or more.

lished. Such compounds may take a form in which they resemble cycliccompounds for example:

in which the several Rs may be similar or dissimilar alkyl, aryl,aralkyl, alkaryl or heterocyclic groups.

The molecular weight and other properties of the organo-silicate varywiththe particular organic radicals The organo-silicatesrepresented byFormulae I and II above wherein R is an alkyl group form a preferredclass of compounds in that these compounds are generally more receptiveto ionizing radiation than the compounds containing aryl or heterocyclicgroups. Of the alkyl substituted compounds, it is preferred to employthose wherein the alkyl radical contains from 1 to 16 carbon atoms and nis a number from 0 to 100. While compounds containing higher alkylgroups can be utilized, if they are liquids insoluble in mineral oils,such compounds may be less effective. Regardless of whether theorgano-silicate is a monomer, dimer, trimer or higher polymerizedproduct, the organo-silicate preferably contains a minimum total ofcarbon atoms. Thus, in Formula I above when R is a methyl radical, n ispreferably at least 3.

When R in Formula I is an ethyl radical, n is preferably at least 1.When R in Formula I is a propyl radical, n In Formula II, when R is amethyl radical, n is zero or more. Generally preferred for the presentpurpose are the relatively high molecular weight irradiated monomerswhere n is zero and R is an alkyl group containing from 8 to 16 carbonatoms. Thus, a preferred class of compounds include tetra octyl orthosilicate, tetra nonyl ortho silicate, tetra decyl ortho silicate, tetraundecyl ortho silicate, tetra dodecyl ortho silicate, tetra tridecylortho silicate, tetra tetradecyl ortho silicate, tetra pentadecyl orthosilicate, and tetra hexadecyl ortho silicate. I

The lower molecular weight compounds, such as when R is a methyl orethyl radical, are polymerized relatively easily and n in such a casemay range from 3 to 100 or more. The higher molecular weight compounds,such as when R is a cety-l radical, are more difficult to condense orpolymerize so that the resulting condensation or polymerization productmay be only a dimer or trimer. Whether the silicate is only a monomer ora highly'p'olymerized product, I prefer to employ an irradiated organosilicate containing a minimum total of 10 carbon atoms. Particularlygood anti-foam characteristics are obtained with an irradiatedorgano-silicate containing a minimum total of 32 to 40 carbon atoms andespecially tetra(diisobutyl carbinyDsilicate which contains a total of36 carbon atoms.

Many of the organo-silicates' utilized according to the presentinvention are available commercially and therefore their .preparationconstitutes no part of the invention. Thus, commercially availableorgano-silicates are time suificient for them to absorb at least about 6megareps. of radiation. The irradiated organo-silicates are thendispersed in the oil.

In the preparation of the lower molecular weight monomers, such as tetramethyl ortho silicate and tetra ethyl ortho silicate, one mol of asilicon halide such as silicon tetrachloride is reacted with four molsof the corresponding alcohol. To obtain the corresponding condensationproducts the tetra alkyl ortho silicates are further heated at refluxingtemperature in the presence of water. In the course of preparing themonomers, four mols of hydrogen chloride are produced for every mol oftetra alkyl ortho silicate. The hydrogen chloride thus formed usuallyconverts some of the alcohol to the ether or alkyl halide and produceswater. The Water thus formed may give rise to the condensation of theintermediate alkoxychlorosilane to form condensed esters such ashexaal-koxydisiloxane, octaalkoxytrisiloxane, decaalkoxytetrasiloxane,and the like.

The higher molecular weight ortho silicates can be 'obtained by an esterexchange reaction with a lower mole'c-ular weight ortho silicate. Tetraoctyl ortho silicate can, for example, be prepared by an ester exchangereaction wi-th tetra methyl ortho silicate or tetra ethyl orthosilicate. The ester exhange reaction can be effected, for example, byheating tetra ethyl ortho silicate with the desired alcohol or mercaptanin the presence of a catalyst such as benzene sulfonic acid or sodiumethoxide. The ester exchange reaction is conducted at a temperature ofabout 100 to 200 C. for a time sufficient to drive off the methyl orethyl alcohol. Thus, in preparing the tetra C to C alkyl orthosilicates, an ester exchange reaction is effected between tetra ethylortho silicate and an alcohol selected from the group'consisting ofoctyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyland hexadecyl alcohols.

The organo-silicate condensation products may be obtained as thepolymerized hydrolysis products of the esters of ortho silicic acid bycontrolled hydrolysis of the tetra orthosilicate esters with water.Hydrolysis and condensation or polymerization take place simultaneouslywith the formation of liquid products which are in general substantiallyinsoluble in hydrocarbon oils and have surface tensions lower than thesurface tensions of such oils. Normally mixtures of products in variousdegrees of polymerization are first obtained. These mixtures afterirradiation may be used directly as anti-foam agents.

It is generally more advantageous, however, to isolate the higher liquidpolymerization products from the total products. In general theeffectiveness of the irradiated organo-silicates in preventing foamformation increases with increased molecular weight and boiling point.Also, the higher molecular weight organo-silica'tes are less soluble inthe hydrocarbon oils. Consequently, it is advantageous to irradiate thehigher boiling liquid fractions of the products. Separation of thedesired fractions may be accomplished by vacuum distillation of thetotal reaction products.

The irradiated organo-silicates as defined hereinabove are effectivefoam inhibitors in very low concentration and although they aresubstantially insoluble in hydrocarbon oils, they are readilydispersible in such oils to form compositions containing stable, finedispersions of the organo-silicate in hydrocarbon oils, which aresubstantially resistant to foam formation, without deleteriouslymodifying the advantageous properties of the oil. Insofar as theorgano-silicate condensation products are concerned, the organo-silicatecondensation products containing simple organic radicals, such asmethyl, ethyl and short-chain alkyl groups are most advantageousinasmuch as they have exceedingly small solubility in most hydro carbonoils. For example, an irradiated fraction of the total reaction productsobtained on hydrolysis and polymerization of tetramethyl orthosilicateand fractionation at 220 to 240 C. at 0.75 mm., which consistspredominantly of a condensation product in which n is of the order of 3,is markedly etfective in concentrations as low as 0.1 percent and less.A similar irradiated fraction obtained by hydrolysis and polymerizationof tetraethyl orthosilicate and fractionation of the products to recoverthe compounds boiling above 290 C. at 1 mm. are also effective inconcentrations as low as 0.005 percent and less.

The organo-silicates as defined hereinabove are for all practicalpurposes substantially oil-insoluble. They are also substantiallyinsoluble in water and aqueous solutions. On the other hand, they can bereadily dispersed in hydrocarbon oils to form stable dispersionscontaining extremely fine particles of irradiated products. In fact, Ihave prepared oil compositions containing such irradiatedorgano-silicates dispersed therein, in which a majority of the dispersedparticles range from 2.0 to 0.3 micron in diameter or less. Such finedispersions of these irradiated silicates in oils are very stable andare markedly resistant to foaming. Some oil compositions containing from5 to 100 parts per million of these compounds finely dispersed thereinyield little or no foam when subjected to drastic foaming tests. Infact, some compositions containing as low as 0.05 part per million of adispersed irradiated silicate show a measurable resistance to foaming.The heavier mineral oils generally require from about 0.00001 to Ipercent by weight to eflfectively reduce foaming. While the irradiatedorgano-silic-ates are for the most part insoluble in mineral oils, someof the organo-silicates may be soluble to a very slight degree. When theirradiated silicate is slightly soluble, the amount of the irradiatedsilicate used should be sufiiciently in excess of its solubility in theoil to give the required amount of dispersed phase necessary to preventfoaming under service conditions. For this reason, the irradiatedorgano-silicates which are substantially oilinsoluble are mostadvantageous.

The particle size of the irradiated organo-silicate dispersed in thehydrocarbon oil has a marked effect upon the resistance to foaming soimparted to the oil compositions. In general, oil compositionscontaining dispersions of the irradiated organo-silicate in which theparticles are about 2.0 microns and less in diameter are particularlyadvantageous for the present purpose. Such oil compositions are verystable in storage and under service conditions, and they have a highresistance to foaming which they retain over long periods of use.

Since good resistance to foaming can be readily obtained withexceedingly small proportions of my new antifoam agents finely dispersedin the oil, the anti-foam agents of my invention do not deleteriouslymodify the other properties of such compositions. Accordingly, thedesired foam-resisting properties can be imparted to such oils withoutimpairing their effectiveness as lubricants or for other intended uses.

In the commercial practice of this invention, oil compositions may beproduced directly in which the antifoam agent is present in the desiredsmall amount and fine dispersion. However, in certain embodiments of theinvention, oil compositions initially containing relatively coarsedispersions and relatively high concentrations of the anti-foam agentmay be first prepared and the desired finely dispersed agentconcentration may be produced in the oil during use by agitation thereofin the lubricating system, such as by gear pumps and other mechanisms.

Such production of the desired fine dispersions in situ in the oilduring use is sometimes advantageous. Of course, the amount of anti-foamagent and the fineness of the dispersion necessary to prevent foaming ina given case vary somewhat with the particular oil and agent employed aswell as the service conditions to which the oil composition issubjected.

In preparing my improved oil compositions, the anti foam agent may beincorporated in the oil or oil composition by any suitable methodcapable of producing a stable fine dispersion of the agent in the oil.For example, where the anti-foam agent is to be added to a heavy mineraloil, it may first be incorporated in a hydrocarbon oil lighter than theoil to be improved, or other suitable carrier, such as mineral seal oil,gasoline, naphtha, hexane and benzene, and this anti-foam compositionmay then be introduced into the oil to which it is desired to giveanti-foam properties. After such an anti-foam composition has beenformed it may be incorporated in the oil or oil composition simply bymixing and agitating the solution therewith. A fine dispersion of theanti-foam agent in the oil is thus obtained. A convenient antifoamconcentrate for such use would contain 1.0 percent of active anti-foamagent. To add 0.001 percent anti foam agent to the final oil wouldrequire the addition of 0.1 percent of the anti-foam concentrate. Whereit is desired to form directly a dispersion of the anti-foam agent inthe oil, various commercial colloid mills may be employed to dispersefinely the agent in the oil. Also, gear pumps may be employed todisperse the anti-foam agent in the oil. The use of such gear pumps isadvantageous in many embodiments of this invention, particularly thosewherein fine dispersions of the anti-foam agents are produced in situ inthe oil. In some instances, the organo-silicate can be added to the oiland then the entire mixture subjected to ionizing radiation. Where suchtechnique is employed, the vehicle should be one that is relativelyinsensitive to radiation under the conditions employed. Other methodsand apparatus may also be employed in dispersing these irradiated agentsin oils or oil compositions.

It is sometimes advantageous to first disperse the liquid anti-foamagent in part of the oil and then add this concentrate dispersion to theremainder of the oil. Such concentrate dispersions can be readilyprepared as stable uniform compositions. For instance, a mixture of oiland anti-foam agent in the desired proportions may be continuouslycirculated through a gear pump until a stable concentrate containing auniform dispersion of the agent is obtained. Thus, standardizedconcentrates can be prepared which can be added to lubricatingcompositions as needed. In such case, the desired amount of concentrateis added to the oil composition and the mixture is agitated untiluniform.

Also, such concentrates are themselves valuable antifoam compositions.As they contain a preformed, dispersed, insoluble liquid phase of thedesired particle size, they quickly break oil foams, as Well as suppressfoaming in general. For instance, when added to oil or oil com positionswhich have foamed, they rapidly destroy the foam present and stopfurther foaming. In such cases, they can be quickly blended with oils,oil compositions and crude oil and uniformly incorporated therein beforeserious foaming occurs.

For such purposes, oil concentrates containing from 0.1 to 10 percent byweight and more of finely dispersed anti-foam agent are advantageous. Byadding from 0.01 to 10 percent by weight of such concentrates to minerallubricating oils, improved lubricants having marked'resistance tofoaming are readily and easily obtained.

fatty oils, and high molecular weight ketones and esters;

viscosity index improvers, such as theihigh molecular and aponr point0150 F. The'tetra(diisobutyl carbinyl)- silicate which'was subjectedtoradiation hada viscosity of 78 SUS at 100 F.. and 37.5 SUS at 210 F. The

' irradiated product as shown hereinabove had no significant change inviscosity and acid value. There was also no noticeable change in color.

Table I Composition, percent by weight A B O D E F G Base 011,27.9API-.-1169 SUS at-100 F 100 99. 95 99.95 99.05 99.- 95 99. 98 99. 9

Tetra (diisobutyl carbinyl) silicate, irradiation dosage, mreps.:

p 50. Foam TestKASTM D892-.46T), Foaming Tendency, m1. at 5 min;

At 7 I At 200 F "weight polymers of isobutylene and the polymers of"metlraerylic esters; pour point depressants, such as a condensationproduct of chlorinated wax and naphthalene and a condensation product ofchlorinated wax and phenol followed by further condensation of thisreaction product with organic acids; an anti-rust agent such ascocoamine isoa-myl octyl orfliophosphate; and corrosion and oxidationinhibitors, such as 2,6-di-tertia-ry butyl-4- methyl 'phenol,*tri-phenylphosphite, tributylphosphite,

beta naphthol, and'phenyl beta naphthylamine.

Many of these agents tend to'promote foaming. The anti-foam product ofmy invention, however, can suppress the foaming caused 'by the additionofsuch agents to an oil without deleteriously affecting the beneficialcharacteristics given to the oil by these additives.

irradiated to various dosages in a Van de Graaff accelerator. The bulktemperature of the tetra(diisobutyl carbinyllsilicate was maintainedbetween about 70 and 200 F.' during irradiation. The total energyabsorption is shown in connection with the'various specific examples. Inpreparing samples of oil for the foam test, the agent was added directlyto the oil. The mixture thus formed was then blended inaWaring'Blendorfor at least five minutes.

The data summarized in Table I will illustrate the advantageous resultsobtained by incorporating in a mineral lubricating oil tetra(diisobutylcarbinyl)silicate which had been subjected to irradiation dosages of 6to 50 megareps. of radiation. A comparison is also made between an oilcontaining no tetra (diisobutyl carbinyl)silicate and also the same oilcontaining irradiated and unirradiated tetradiisob'utylearbinyD'silicate.

The mineral ilubricating oilused in preparing the compositionsillustrated in Table I was a highly refined paraffinic minerallubricating oil of SAE '50'grade having an APYgravity' ot27.9,1aviscosity of 1169 SUS'at-100" F. and 100 SUS ED12210 F.,'a'viscosity index of 101, a flash perm OQC.) "of 570F., a firepoint'(iO.C.)"0f 625 F.

As shown by the data summarized in TableI, the addition of unirradiatedtetra(diisobutyl carbinyl)si1icate decreasedthe amount of foam formedinthe oil when tested at 75 F. However, when the same-oil'was maintainedat 200 F., the unirradiated tetra(diisobutyl carbinyl)silicate increasedthe foaming tendency of the oil. The addition of tetra(diisobutylcarbinyl)silicate which was irradiatedto dosages of 6 to 50.megareps.re-

duced the foaming tendency of the oil at 75 F. and also at 200 F. Theimproved anti-foam characteristics of compositions of the invention, forexample,- compositions C to G, is thus readily apparent.

Other specific organo-silicates which when irradiated are useful for thepresent purpose are tetra methyl .ortho silicate condensation productsand tetra ethyl ortho silicate condensation products wherein nin FormulaI shown hereinabove is 3. The condensationproducts of tetra methyl orthosilicate and tetra ethylaortho silicate can be obtained by heating therespective silicates at refluxing'temperature' for about 2m 3 hours inthe presence of'the corresponding alcohols and water in such proportionas to provide about 0.8 mol of water per mol of silicate. The alcoholand uncondensed ortho silicate are then distilled off at atmosphericpressure. The condensation products are then fractionally distilled atabout 1 mm. of mercury pressure. The-fractions thus obtained are thensubjected to ionizing radiation for a time suflicient for thecondensation product to absorb at least 6 megareps; ofradiation.

Still other specific organo-silicates include irradiated tetra propylortho silicate, tetra butyl orthosilicate, tetra pentyl .ortho silicate,tetra 'hexyl ortho silicate, tetra heptyl ortho silicate, tetra octylortho silicate, tetra nonyl ortho silicate, tetra decyl ortho silicate,tetra undecyl orthosilicate, tetra dodecyl ortho silicate, tetratridecyl ortho silicate, tetra tetradecyl ortho silicate, tetrapentadecyl ortho silicate, tetra'hexadecyl'ortho silicate, 'tetra phenylortho silicate, tetra tolyl ortho silicate, tetra benzyl ortho silicate,tetra furyl ortho silicate, tetra thienyl orho silicate, tetra pyrrylortho silicate, tetra"pyridyl ortho silicate, tetra dichloro phenylortho silicate, dimethyl dibutyl ortho silicate, dibutyl'dioctyl orthosilicate, dimethyl diphenyl ortho silicate, tetra decenyl' orthosilicate, tetra 'butoxyethyl ortho'silicate, and their condensation orpolymerization products.

I 1 stantially the same as those of the base oil as shown by theinspection data in the following Table II.

Table II Mineral Oil+0.05% by weight 50 mrep lrradiate tra (diisobutylcarbinyl) silicate Composition Mineral Oil Gravity, API Viscosity, SUS:

at 100 F Viscosity Inde. Flash Point F- Fire Point (00), F-.- PourPoint, F Color, ASTM Union. Ash, Percent While my invention has beendescribed above with reference to various specific examples andembodiments, it Will be understood that the invention is not limited tosuch illustrative examples and embodiments, and may be variouslypracticed within the scope of the claims hereinafter made.

I claim:

1. A process of suppressing foaming in a mineral lubricating oil havingfoaming tendencies comprising dispersing in said oil a small amount,sufficient to improve said foaming tendencies, of a liquidorgano-silicate which has been subjected to ionizing radiation for timesufficient for said organo-silicate to absorb about 6 to about 1000megareps. of radiation while maintaining the bulk temperature of theorgano-silicate below its decomposition temperature, saidorgano-silicate being selected from the group consisting of alkyl, aryl,aralkyl, alkaryl and heterocyclic ortho silicates containing a minimumtotal of 10 carbon atoms.

2. The process of claim 1 wherein the amount of organo-silicatedispersed in said oil is about 0.00001 to about 1.0 percent by weight ofthe oil.

3. A process of suppressing foaming in a mineral lubricating oil havingfoaming tendencies comprising dispersing in said oil a small amount,sufficient to improve said foaming tendencies, of a liquid alkyl orthosilicate which has been subjected to ionizing radiation for a timesufficient for said alkyl ortho silicate to absorb about 6 to about 1000megareps. of radiation while maintaining the bulk temperature of thealkyl ortho silicate below its decomposition temperature, said alkylortho silicate containing a minimum total of 10 carbon atoms.

4. The process of claim 2 wherein the alkyl radical of said alkyl orthosilicate contains from 1 to 16 carbon atoms.

5. A process of suppressing foaming in a mineral lubricating oil havingfoaming tendencies comprising dispersing in said oil a small amount,sufficient to improve said foaming tendencies, of a liquid tetra alkylortho silicate which has been subjected to ionizing radiation for a timesuflicient for said tetra alkyl ortho silicate to absorb about 6 toabout 1000 megareps. of radiation while maintaining the bulk temperatureof the tetra alkyl ortho silicate below its decomposition temperature,said tetra alkyl ortho silicate containing a minimum total of 10 carbonatoms.

6. The process of claim wherein the tetra alkyl ortho silicate istetra(diisobutyl carbinyl)silicate.

7. A process of suppressing foaming in a mineral lubricating oil havingfoaming tendencies comprising dis persing in said oil a small amount,sufiicient to improve said foaming tendencies, of a liquid ethyl orthosilicate condensation product which has been subjected to ionizingradiation for a time suflicient for said condensation product to absorbabout 6 to about 1000 megareps. of radiation while maintaining the bulktemperature of the condensation product below its decompositiontemperature, said condensation product containing a minimum total of 10carbon atoms.

8. A process of suppressing foaming in a mineral lubricating oil havingfoaming tendencies comprising dispersing in said oil a small amount,sufiicient to improve said foaming tendencies, of a liquid methyl orthosilicate condensation product which has been subjected to ionizingradiation for a time sufficient for said con densation product to absorbabout 6 to about 1000 megareps. of radiation while maintaining the bulktemperature of the condensation product below its decompositiontemperature, said condensation product containing a minimum total of 10carbon atoms.

9. A process of suppressing foaming in a mineral lubricating oil havingfoaming tendencies comprising dispersing in said oil a small amount,sufiicient to improve said foaming tendencies, of a liquidorgano-silicate which has been subjected to ionizing radiation for atime sufiicient for said organo-silicate to absorb about 6 to about 1000megareps. of radiation while maintaining the bulk temperature of thecondensation product below its decomposition temperature, the dispersionin said oil having been formed by dispersing a mixture of saidorgano-silicate in a hydrocarbon oil lighter than the oil in whichfoaming is to be suppressed, said mixture containing about 0.1 to about10 percent by weight of said organo-silicate and said organo-silicatebeing selected from the group consisting of alkyl, aryl, aralkyl,alkaryl and heterocyclic ortho silicates containing a minimum total of10 carbon atoms.

10. A lubricating oil composition of reduced foaming propertiescomprising a major. amount of a mineral lubricating oil having foamingtendencies and a small amount, sufiicient to improve said foamingtendencies, of a liquid organo-silicate which has been subjected toionizing radiation for a time sufficient for said organo-silicate toabsorb about 6 to about 1000 megareps. of radiation while maintainingthe bulk temperature of the organo-silicate below its decompositiontemperature and which is stably dispersed in the oil, saidorgano-silicate being selected from the group consisting of alkyl, aryl,aralkyl, alkaryl and heterocyclic ortho silicates, containing a minimumtotal of 10 carbon atoms.

11. A lubricating oil composition of reduced foaming propertiescomprising a major amount of a mineral lubricating oil having foamingtendencies and a small amount, sufficient to improve said foamingtendencies, of a liquid alkyl ortho silicate which has been subjected toionizing radiation for a time sufficient for said alkyl ortho silicateto absorb about 6 to about 1000 megareps. of radiation while maintainingthe bulk temperature of the alkyl ortho silicate below its decompositiontemperature and which is stably dispersed in the oil, said alkyl orthosilicate containing a minimum total of 10 carbon atoms.

12. A lubricating oil composition of reduced foaming propertiescomprising a major amount of a mineral lubricating oil having foamingtendencies and a small amount, sufiicient to improve said foamingtendencies, of a liquid alkyl ortho silicate which has been subjected toionizing radiation for a time sufficient for said alkyl ortho silicateto absorb about 6 to about 1000 megareps. of radiation while maintainingthe bulk temperature of the alkyl ortho silicate below its decompositiontemperature and which is stably dispersed in the oil, said alkyl orthosilicate containing a minimum total of 10 carbon atoms and the alkylradical in said alkyl ortho silicate containing from 1 to 16 carbonatoms.

13. A lubricating oil composition of reduced foaming propertiescomprising a major amount of a mineral lubricating oil having foamingtendencies and a small amount, sufiicient to improve said foamingtendencies, of a liquid tetra alkyl ortho silicate which has beensubjected to ionizing radiation for a time suificient for said tetraalkyl ortho silicate to absorb about 6 to about 1000 megareps. ofradiation while maintaining the bulk temperature of the tetra alkylortho silicate below its decomposition temperature and which is stablydispersed in the oil, saidtetra alkyl ortho silicate containing aminimum total of 10 carbon atoms.

14. The lubricating oil composition of claim 13 wherein the tetra alkylortho silicate is tetra(diisobutyl carbinyl)silicate.

15. A lubricating oil composition of reduced foaming propertiescomprising a major amount of a mineral lubricating oil having foamingtendencies and a small amount, sufficient to improve said foamingtendencies, of a liquid ethyl ortho silicate condensation product whichhas been subjected to ionizing radiation for a time sufficient for saidcondensation product to absorb about 6 to about 1000 megareps. ofradiation while maintaining the bulk temperature of the condensationproduct below its decomposition temperature and which is stablydispersed in the oil, said condensation product containing a minimumtotal of 10 carbon atoms.

16. A lubricating oil composition of reduced foaming propertiescomprising a major amount of a mineral lubricating oil having foamingtendencies and a small amount, sufiicient to improve said foamingtendencies, of a liquid methyl ortho silicate condensation product whichhas been subjected to ionizing radiation for a time sufficient for saidcondensation product to absorb about 6 to about 1000 megareps. ofradiation while maintaining the bulk temperature of the condensationproduct below its decomposition temperature and which is stablydispersed in the oil, said condensation product containing a minimumtotal of 10 carbon atoms.

17. A lubricating oil composition of reduced foaming propertiescomprising a major amount of a mineral lubricating oil having foamingtendencies and about 0.00001 to about 1.0 percent by weight sufficientto improve said foaming tendencies of a liquid organo-silicate which hasbeen subjected to ionizing radiation for a time sufiicient for saidorgano-silicate to absorb about 6 to about 1000 megareps. of radiationwhile maintaining the bulk temperature of the organo-silicate below itsdecomposition temperature and which is stably dispersed in the oil, saidorgano-silicate being selected from the group consisting of alkyl, aryl,aralkyl, alkaryl and heterocyclic ortho silicates containing a minimumtotal of 10 carbon atoms.

18. A lubricating oil composition of reduced foaming propertiescomprising armajor amount of a mineral lubricating oil having foamingtendencies and about 0.00001 to about 1.0 percent by weight suflicientto improve said foaming tendencies of a liquid tetra alkyl orthosilicate which has been subjected to ionizing radiation for a timesufiicient for said tetra alkyl ortho silicate to absorb about 6 toabout 1000 megareps. of radiation while maintaining the bulk temperatureof the tetra alkyl ortho silicate below its decomposition temperatureand which is stably dispersed in the oil, said tetra alkyl orthosilicate containing a minimum total of 10 carbon atoms.

19. The lubricating oil composition of claim 18 wherein the tetra alkylortho silicate is tetra(diisobutyl carbinyl) silicate.

20. A composition adapted to impart foam resisting properties to amineral lubricating oil having foaming tendencies when added thereto inan amount corresponding to about 0.01 to about 10 percent by weight,comprising a major amount of a hydrocarbon liquid containing from about0.1 to about 10 percent by Weight of a liquid organo-silicate which hasbeen subjected to ionizing radiation for a time sufiicient for saidorgano-silicate to absorb at least about 6 to about 1000 megareps. ofradiation while maintaining the bulk temperature of the organo-silicatebelow its decomposition temperature, said organo-silicate being selectedfrom the group consisting of alkyl, aryl, aralkyl, alkaryl andheterocyclic ortho silicates containing a minimum total of 10 carbonatoms.

21. A lubricating oil composition of reduced foaming propertiescomprising a major amount of a mineral lubricating oil having foamingtendencies and about 0.00001 to about 1.0 percent by weight, sufficientto improve said foaming tendencies, of tetra(diisobutylcarbinyl)silicate,

which has been subjected to ionizing radiation for a time suflicient toabsorb about 6 to about megareps. of radiation while maintaining thebulk temperature of the tetra(diisobutyl carbinyl)silicate below itsdecomposition temperature.

References Cited in the file of this patent UNITED STATES PATENTS2,375,007 Larsen et al. May 1, 1945 2,416,504 Trautman et al. Feb. 25,1947 2,632,736 Currie Mar. 24, 1953 2,702,793 Smith Feb. 22, 19552,766,220 Kantor Oct. 9, 1956 2,904,481 Lawton et al. Sept. 15, 1959OTHER REFERENCES Charlesby: Effect of Molecular Weight on the Cross-Linking of Siloxanes by High-energy Radiation, Nature, vol. 173, April10, 1954, pp. 679,680.

UNITED STATES P ATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 O33,788 May 8 1962 Charles E, Trautman It is hereby certified that errorappears in 1: ant requiring correction and that the s corrected below.

Column 2, line 6, for "he" read the column 4 line 42, strike out"aralkyl ortho silicates,"; column 1.1 line 54, for the claim referencenumeral "2" read 3 S1gned and sealed th1s 28th day of August .1962

(SEAL) Attest:

ESTON G. JOHNSON DAVID L. LADD Attesting Officer Commissioner of Patents

10. A LUBRICATING OIL COMPOSITION OF REDUCED FOAMING PROPERTIESCOMPRISING A MAJOR AMOUNT OF A MINERAL LUBRICATING OIL HAVING FOAMINGTENDENCIES AND A SMALL AMOUNT, SUFFICIENT TO IMPROVE SAID FOAMINGTENDENCIES, OF A LIQUID ORGANO-SILICATE WHICH HAS BEEN SUBJECTED TOIONIZING RADIATION FOR A TIME SUFFICIENT FOR SAID ORGANO-SILICATE TOABSORB ABOUT 6 TO ABOUT 1000 MEAGAREPS. OF RADIATION WHILE MAINTAININGTHE BULK TEMPERATURE OF THE ORGANO-SILICATE BELOW ITS DECOMPOSITIONTEMPERATURE AND WHICH IS STABLY DISPERSED IN THE OIL, SAIDORGANO-SILICATE BEING SELECTED FROM THE GROUP CONSISTING OF ALKYL, ARYL,ARALKYL, ALKARYL AND HETEROCYCLIC ORTHO SILICATES, CONTAINING A MINIMUMTOTAL OF 10 CARBON ATOMS.